Silica gel incorporating polyazacycloalkane structural units

ABSTRACT

A novel compound which can be used in the field of separation and purification of gases is disclosed. The compound can be incorporated into a silica gel incorporating polyazacycloalkane structural units for separating a predetermined gas from a mixture of gases. The mixture of gases is brought into contact with a metallated hybrid gel under conditions which make possible the absorption of the gas to be separated, followed by a phase of desorption of the attached gas, and the recovery of the gas.

This application is a 371 of PCT/FR 99/00142 filed Jan. 25, 1999.

A novel material which can be used in the field of the separation andpurification of gases is disclosed. Current separation techniques,whether cryogenic distillation or adsorption on zeolites, and techniquesfor the purification of industrial gases by cryogenic or catalyticdistillation are not always capable of being optimized, either ineconomic terms or in terms of purity. Many studies have furthermoreshown that gases such as oxygen, hydrogen or carbon monoxide reactselectively and reversibly with transition metal complexes.

BACKGROUND OF THE INVENTION

Thus, cobalt(II) complexes of cyclam or of cyclene easily fixatmospheric oxygen (Machida R., Kimura E., Kodama M., Inorg. Chem.,1983, 22, 2055-2061) and result in μ-peroxide species in aqueous media.However, the lifetime of the oxygen-comprising complexes in solution islimited as the latter can undergo irreversible decomposition reactions(Martell A. E., Basak A. K., Raleigh. C. J., Pure Appl. Chem., 1988, 60,1325-1329). Furthermore, these species cannot be deoxygenated simply bydecreasing the dioxygen partial pressure. An improvement in thereversibility, necessary in a separation process, requires stabilizationof the intermediate superoxide species. Grafting the ligand to a solidmatrix should, at the same time, slow down the change from thesuperoxide species to the μ-peroxide species, restrict hydrolysisreactions and facilitate the handling of the active complex (TsuchidaE., Nishide, H. Top. Curr. Chem., 1986, 32, 63-99). The incorporation ofcobalt complexes with porphyrins, phthalocyanines or cyclidenes inorganic or inorganic polymers, such as silica gels, and the study of theinteraction of these materials with oxygen have already formed thesubject of numerous studies. Generally, the complex is synthesized in afirst stage and then immobilized on the polymer via a dative bondbetween a nitrogen atom of a pyridine or imidazole unit and the metal(Nishide H., Suzuki T., Kawakami H., Tsuchida E., J. Phys. Chem., 1994,98, 5084-5088; Cameron J. H., Graham S., J. Chem. Soc. Dalton Trans.,1992, 385-391; Bowman R. G., Basolo F., Burwell Jr. R. L., J. Am. Chem.Soc., 1975, 97, 5125-5129). Another approach consists in attaching, in afirst step, the ligand to the polymer via a covalent bond and insubsequently metallating (Wöhrle D., Gitzel J., Krawczyk G., TsuchidaE., Ohno H., Okura I., Nishisaka T., J. Macromol. Sci. Chem., 1988, A25,1227-1254; Barnes M. J., Drago R. S., Balkus Jr. K. J., J. Am. Chem.Soc., 1988, 110, 6780-6785). Thus, the grafting to silica gel oftetraazamacrocyclic ligands and the study of the metallation of thesematerials have been carried out (Gros C., Rabiet F., Denat F., BrandesS., Chollet H., Guilard R., J. Chem. Soc. Dalton Trans., 1996,1209-1214). The sol-gel process has been studied in detail (Hench L. L.,West J. K., Chem. Rev., 1990, 90, 33-72) and is of major importance inthe chemistry of the materials. One of the main advantages of thisprocess is a high homogeneity of the materials obtained, thus conferringspecific properties on them. Precursors of alkoxide type are among themost widely used. Thus, the hydrolysis of tetraethoxysilane in solutionin an organic solvent, for example an alcohol, results in a colloidaldispersion of particles, which particles result from the polymerizationof the precursor and which dispersion is referred to as a sol. This solchanges in the direction of the formation of a gel. The drying of thisgel by evaporation results in a xerogel, which can itself be convertedinto glass or ceramic. More recently, this technique has made possiblethe preparation of novel organic-inorganic hybrid materials (Corriu R.J. P., Leclercq D., Angew. Chem. Int. Ed., 1996, 35, 1420-1436; SchubertU., Hüsing N., Lorenz A., Chem. Mater., 1995, 7, 2010-2027). Theprecursor is then an organic compound carrying one or more endings oftrialkoxysilyl [Si(OR₃)] or silyl [SiH₃] type. Various organic specieshave been used, such as aromatic compounds, acetylenic units or linearand cyclic amines (Corriu R. J. P., Leclercq D., Angew. Chem. Int. Ed.,1996, 35, 1420-1436; Khatib I. S., Parish R. V., J. Organomet. Chem.,1989, 369, 9-16; Tsuda T., Fujiwara T., J. Chem. Soc. Chem. Commun.,1992, 1659-1661). Battioni et al. have used this route to incorporatemanganese and iron porphyrins in a silica gel and have tested thecatalytic properties of these novel materials (Battioni P., Cardin E.,Louloudi M., Schöllhorn B., Spyroulias G. A., Mansuy D., Traylor T. G.,Chem. Commun., 1996, 2037-2038).

SUMMARY OF THE INVENTION

The anchoring of a complex to a polymer via a dative bond between a baseand the metal exhibits the advantage of activating the complex and ofstabilizing the superoxide species by hindering one of the faces of thecomplex. However, the bond thus formed is weak. The grafting of theligand via a covalent bond results, for its part, in a strongermaterial. Generally, the methods for the incorporation of the transitionmetal complexes in organic or inorganic matrices have to date beenunable to result in materials which are compatible with the requirementsof process engineering and can thus be used in industrial processes. Inparticular, the characteristics of such a material must be able to beadjusted in terms of specific surface, of porosity, whether this be theradius, the shape or the size distribution of the pores, and of particlesize. The Applicant Company has found that the material which is asubject-matter of the present invention makes it possible to solve theproblems set out hereinabove. A subject-matter of the invention is acompound of formula (I):

in which:

W₁, W₂ and W₃, which are identical or different, each represent,independently of one another, a divalent radical chosen from thoserepresented by the general formula (A):

—[(CT₁T₂)_(n)—[N(R₄)]_(p)—(CT₃T₄)_(m)]_(l)—  (A)

 in which:

p represents an integer equal to 0 or to 1,

l represents an integer equal to 1 or to 2,

n and m, which are identical or different, each represent, independentlyof one another, an integer less than or equal to 3 and greater than orequal to 1, T₁, T₂, T₃ and T₄, which are identical or different, eithereach represent, independently of one another, a hydrogen atom, a linearor branched alkyl radical comprising from 1 to 15 carbon atoms or a[(hetero)aryl]alkyl radical comprising from 7 to 12 carbon atoms or elseCT₁T₂ and/or CT₃T₄ represent a divalent group —(C═O)—,

R₄ represents a hydrogen atom, a linear or branched alkyl radicalcomprising from 1 to 15 carbon atoms which is unsubstituted orsubstituted by one or more functional groups, a [(hetero)aryl]alkylradical comprising from 7 to 12 carbon atoms or a radical represented bythe general formula (B):

R₅—Si(X₁)(X₂)(X₃)  (B)

 in which:

X₁, X₂ and X₃, which are identical or different, each represent,independently of one another, a hydrogen atom, a halogen atom or an OR₆radical, in which R₆ represents a hydrogen atom or an alkyl radicalcomprising from 1 to 4 carbon atoms,

R₅ represents a divalent radical derived from a saturated or unsaturatedaliphatic hydrocarbonaceous chain comprising from 1 to 10 carbon atoms,in which chain are optionally inserted one or more structural linkschosen from the arylene group or the —O—, —S—, —O—C(═O)—, —N(R₇)—C(═O)—or —N(R₇)— fragments, in which fragments R₇ represents a hydrogen atom,an aliphatic hydrocarbonaceous radical comprising from 1 to 6 carbonatoms, a benzyl radical or a phenethyl radical, said chain beingunsubstituted or substituted by one or more radicals chosen from halogenatoms, the hydroxyl group, alkyl radicals comprising from 1 to 4 carbonatoms or benzyl or phenethyl radicals,

R₁, R₂ and R₃, which are identical or different, each represent,independently of one another and of R₄, a hydrogen atom, a linear orbranched alkyl radical comprising from 1 to 15 carbon atoms which isunsubstituted or substituted by one or more functional groups, a[(hetero)aryl]alkyl radical comprising from 7 to 12 carbon atoms or aradical represented by the general formula (B) as defined above, itbeing understood that at least one of these cyclic nitrogens issubstituted by a radical of formula (B).

DETAILED DESCRIPTION OF THE INVENTION

Mention may be made, as compounds of formula (I) comprising three cyclicnitrogen atoms, of, for example, the compounds derived from1,4,7-triazacyclononane, from 1,4,7-triazacyclodecane or from1,5,8-triazacyclododecane. Mention may be made, as compounds of formula(I) comprising four cyclic nitrogen atoms, of, for example, thecompounds derived from 1,4,7,10-tetraazacyclododecane (cyclene), from1,4,7,10-tetraazacyclotridecane, from 1,4,7,10-tetraazacyclotetradecane,from 1,4,8,11-tetraazacyclotetradecane (cyclam), from1,4,8,12-tetraazacyclopentadecane, from 1,5,9,13-tetraazacyclohexadecaneor from 1,5,10,14-tetraazacyclooctadecane. Mention may be made, ascompounds of formula (I) comprising five cyclic nitrogen atoms, of, forexample, the compounds derived from 1,4,7,10,13-pentazacyclopentadecane,from 1,4,7,11,15-pentaazacycloctadecane or from1,5,9,13,17-pentaazacyclooctadecane.

Mention may be made, as compounds of formula (I) comprising six cyclicnitrogen atoms, of, for example, the compounds derived from1,4,7,10,13,16-hexaazacyclooctadecane or from1,5,9,13,17,20-hexaazacyclotetracosane.

The term “functional group” denotes in particular, in the definitions ofR₁, R₂, R₃ and R₄, the carboxyl (CO₂H), carboxamido (CONH₂), sulfo(SO₃H) or dihydrophosphonato (PO₃H₂) groups, in the esterified form.

A particular subject-matter of the invention is,

either a compound of formula (Ia), corresponding to the formula (I) asdefined above in which W₁, W₂ and W₃, which are identical or different,represent a radical of formula (A₁), corresponding to the formula (A) asdefined above in which p is equal to 0 and the sum n+m is equal to 2 orto 3,

or a compound of formula (Ib), corresponding to the formula (I) in whichW₁ represents a divalent radical of formula (A₂), corresponding to theformula (A) as defined above in which p is equal to 1 and the sum n+m isequal to 2 or to 3, and W₂ and W₃, which are identical or different,represent a radical of formula (A₁),

or a compound of formula (Ic), corresponding to the formula (I) in whichW₁ and W₂, which are identical or different, represent a divalentradical of formula (A₂) and W₃ represents a radical of formula (A₁).

A more particular subject-matter of the invention is,

either the compound of formula (Ia₁), corresponding to the formula (Ia)as defined above in which l is equal to 1 and either W₁, W₂ and W₃ eachrepresent the divalent radical —CH₂—CH₂—CH₂— or else any one of thethree groups W₁, W₂ or W₃ represents the divalent radical —CH₂—CH₂—CH₂—and each of the other two groups represents the divalent radical—CH₂—CH₂—,

or the compound of formula (Ib₁), corresponding to the formula (Ib) asdefined above in which l is equal to 1 and either any one of the threegroups W₁, W₂ or W₃ represents the radical —CH₂—CH₂—CH₂—N(R₄)—CH₂—CH₂—,either one of the two remaining groups represents the radical —CH₂—CH₂—and the final group represents the radical —CH₂—CH₂—CH₂— or else any oneof the three groups W₁, W₂ or W₃ represents the radical—CH₂—CH₂—CH₂—N(R₄)—CH₂—CH₂—CH₂— and the other two groups each representthe radical —CH₂—CH₂—CH₂—.

The compound of formula (I) can be unsubstituted or substituted; when itis substituted, it is, for example, that substituted by one or morealkyl radicals comprising from 1 to 15 carbon atoms or the benzyl,picolyl or phenethyl radicals, such as, for example,6-dodecyl-1,4,8,11-tetraazacyclotetradecane,3-dodecyl-1,5,9,13-tetraazacyclohexadecane,3-dodecyl-1,5,10,14-tetraazacyclooctadecane,5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane,1,4,7,10,13-pentaethyl-1,4,7,10,13,16-hexaazacyclooctadecane,1,4,7,10-tetraethyl-1,4,7,10,13-pentaazacyclopentadecane,1-methyl-1,4,8,11-tetraazacyclotetradecane,1-benzyl-1,4,8,11-tetraazacyclotetradecane,1-[(2-pyridyl)methyl]-1,4,8,11-tetraazacyclotetradecane,1-[(3-pyridyl)methyl]-1,4,8,11-tetraazacyclotetradecane or1,4-dibenzyl-1,4,8,11-tetraazacyclotetradecane.

According to a specific aspect of the present invention, asubject-matter of the latter is the compounds of formulae (Ia), (Ib) and(Ic) as defined above in which the R₁, R₂, R₃ and R₄ radicals representeither a (B) radical or a hydrogen atom and in particular the compoundsof formulae (Ia₁) and (Ib₁) as defined above in which the R₁, R₂, R₃ andR₄ radicals represent either a (B) radical or a hydrogen atom.

According to another specific aspect of the present invention, asubject-matter of the latter is the compound of formula (I) as definedabove in which R₁, R₂, R₃ and R₄ represent either a (B) radical or aradical —(CH₂)_(w)—C(═O)—V, in which V represents one of the NH₂ or OR₈radicals, in which R₈ represents an alkyl radical comprising from 1 to 4carbon atoms, and w represents an integer greater than or equal to 1 andless than or equal to 6.

The radical of formula (B) as defined above is, for example, a radicalof formula (B₁):

—[CH₂—CH(OH)]_(y)—(CH₂)_(o)—(Q)_(q)—(CH₂)_(r)—(Ar)_(s)—(CH₂)_(t)—(U)_(u)—(CH₂)_(v)—Si(X)₃  (B₁)

in which:

o, r, t and v, which are identical or different, each represent,independently of one another, an integer greater than or equal to 0 andless than or equal to 6,

y, q, s and u, which are identical or different, represent,independently of one another, an integer greater than or equal to 0 andless than or equal to 1,

Q and U, which are identical or different, each represent, independentlyof one another, an oxygen atom, a sulfur atom or one of the —O—CO—,—CO—O—, —NH—CO—, —CO—NH— or —NH— groups,

Ar represents an arylene group and in particular a phenylene group,

X represents a hydrogen atom or one of the methoxy or ethoxy radicals,

it being understood,

that, when q is equal to 1, the sum y+o is other than 0,

that, when q is equal to 1 and when u is equal to 0, the sum r+s+t+v isother than 0,

that, when u is equal to 1, v is other than 0,

that, when u is equal to 1 and when q is equal to 0, the sum y+o+r+s+tis other than 0,

that, when s is equal to 0 and when q and u are each equal to 1, the sumr+t is other than 0, and

that the sum y+o+r+t+v is less than or equal to 12.

In a preferred alternative form of the present invention, the radical offormula (B₁) as defined above is chosen from the 3-silylpropyl,(4-silylphenyl)methyl, 3-(triethoxysilyl)propyl,3-[[3-(triethoxysilyl)propyl]oxy]-2-hydroxypropyl,[4-[[[3-(triethoxysilyl)propyl]amino]methyl]phenyl]methyl,[4-(triethoxysilyl)phenyl]propyl,3-oxo-3-[[3-(triethoxysilyl)propyl]oxy]propyl or2-oxo-2-[[3-(triethoxysilyl)propyl]amino]ethyl radicals.

A very particular subject-matter of the invention is the compounds withthe following names:

1,4,8,11-tetrakis[3-(triethoxysilyl)propyl]-1,4,8,11-tetraazacyclotetradecane,

1,4,8,11-tetrakis[[4-(triethoxysilyl)phenyl]methyl]-1,4,8,11-tetraazacyclotetradecane,

tetra[3-(triethoxysilyl)propyl]1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrapropanoate,

1,4,8,11-tetrakis(3-silylpropyl)-1,4,8,11-tetraazacyclotetradecane,

1,4,8,11-tetrakis[(4-silylphenyl)methyl]-1,4,8,11-tetraazacyclotetradecane,

N₁,N₂,N₃,N₄-tetrakis[3-(triethoxysilyl)propyl]-1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetamide,

4,11-bis[[4-(triethoxysilyl)phenyl]methyl]-1,4,8,11-tetraazacyclotetradecane-7,14-dione.

According to another aspect of the present invention, a subject-matterof the latter is a process for the preparation of the compound offormula (I) as defined above, which comprises

a) the reaction of a compound of formula (C)

Z—R′₅—Si(X₁)(X₂)(X₃)  (C)

 in which:

X₁, X₂ and X₃, which are identical or different, each represent,independently of one another, a hydrogen atom, a halogen atom or an OR₆radical, in which R₆ represents a hydrogen atom or an alkyl radicalcomprising from 1 to 4 carbon atoms,

R′₅ represents a divalent radical derived from a saturated orunsaturated aliphatic hydrocarbonaceous chain comprising from 1 to 10carbon atoms, in which chain are optionally inserted one or morestructural links chosen from the arylene group or the —O—, —S—,—O—C(═O)—, —N(R₇)—C(═O)— or —N(R₇)— fragments, in which fragments R₇represents a hydrogen atom, an aliphatic hydrocarbonaceous radicalcomprising from 1 to 6 carbon atoms, a benzyl radical or a phenethylradical, said chain being unsubstituted or substituted by one or moreradicals chosen from halogen atoms, the hydroxyl group, alkyl radicalscomprising from 1 to 4 carbon atoms or the benzyl or phenethyl radicals,

Z represents a functional group capable of reacting with a secondaryamine functional group, ═N—H, to form an N—C covalent bond,

with a compound of formula (I′):

in which:

W′₁, W′₂ and W′₃, which are identical or different, each represent,independently of one another, a divalent radical chosen from thoserepresented by the general formula (A′):

—[(CT₁T₂)_(n)—[N(R′₄)]_(p)—(CT₃T₄)_(m)]_(l)—  (A′)

 in which,

l, p, n, m, T₁, T₂, T₃ and T₄ have the same definition as for theformula (A) as defined above and

R′₄ represents a hydrogen atom, a linear or branched alkyl radicalcomprising from 1 to 15 carbon atoms or a [(hetero)aryl]alkyl radicalcomprising from 7 to 12 carbon atoms,

R′₁, R′₂ and R′₃, which are identical or different, each represent,independently of one another and of R₄, a hydrogen atom, a linear orbranched alkyl radical comprising from 1 to 15 carbon atoms or a[(hetero)aryl]alkyl radical comprising from 7 to 12 carbon atoms,

it being understood that the polyazacycloalkane nucleus of the compoundof formula (I) comprises at most 30 cyclic carbon atoms and at most 6cyclic nitrogen atoms and that at least one of these cyclic nitrogenatoms is

to form the compound of formula (I) as defined above and, if desired,

b) the functionalization of all or a portion of the unsubstituted cyclicnitrogens of said compound of formula (I) to form a compound of formula(Id), corresponding to the formula (I) as defined above in which atleast one of the R₁, R₂, R₃ or R₄ radicals represents a radical—(CH₂)_(w)—C(═O)—V in which w and V are as defined above.

The term “functional group capable of reacting with a secondary amine”denotes in particular those which react according to a nucleophilicsubstitution mechanism, such as, for example, halogen radicals and inparticular the bromo or iodo radicals, or those which react according toan electrophilic addition mechanism, such as, for example, the epoxyfunctional group, which results in an N—CH₂—CH(OH)— fragment; it canalso be a free, salified or esterified carboxyl functional group or anunsaturated group CH₂═CH—, which results in an N—CH₂—CH₂— fragment by areaction of “Michael” type according to a nucleophilic additionmechanism.

These examples do not have a limiting nature and it is obvious that anyfunctional group known to a person skilled in the art at the date offiling of the present patent application as being capable of reactingwith a secondary amine functional group to form an N—C covalent bondforms an integral part of the description of the present invention.

The compounds of formula (C₁):

Z′—(CH₂)_(o)—(Q)_(q)—(CH₂)_(r)—(Ar)_(s)—(CH₂)_(t)—(U)_(u)—(CH₂)_(v)—Si(X)₃(C₁)

in which:

o, q, r, s, t, u, v, Q, Ar, U and X have the same definition as for theformula (B₁) as defined above,

Z′ represents either a halo radical, in particular a bromo radical or aniodo radical, or an oxiran-2-yl group or an ethenyl group,

the sum q+s is equal to 0 or to 1, it being understood that, when q isequal to 1 and when Z′ represents a halo radical, o is other than 0,

that, when q is equal to 1 and when u is equal to 0, the sum r+s+t+v isother than 0,

that, when u is equal to 1, v is other than 0,

that, when u is equal to 1 and when q is equal to 0, the sum o+r+s+t isother than 0,

that, when s is equal to 0 and when q and u are each equal to 1, the sumr+t is other than 0, and

that the sum o+r+t+v is less than 6,

and in particular (triethoxy)(3-iodopropyl)silane,2-[[[3-(triethoxysilyl)propyl]oxy]methyl]oxirane,N-[[4-(bromomethyl)phenyl]methyl]—N-[3-(triethoxysilyl)propyl]amine,(triethoxy)[4-(iodomethyl)phenyl]silane, 3-(triethoxysilyl)propylpropenoate or N-[3-(triethoxysilyl)propyl]bromoacetamide, areparticularly appropriate in carrying out the process according to theinvention.

According to another aspect of the present invention, a subject-matterof the latter is a polysiloxane gel (III) incorporatingpolyazamacrocycles and metal complexes of these nitrogenous ligands,which is capable of being obtained from the hydrolysis of the compoundof formula (I) as defined above, resulting in the formation of apolysiloxane gel incorporating non-metallated polyazamacrocycle units(III′), followed by the action of a metal salt on said gel (III′), andthe process for the preparation of the polysiloxane gel (III′) thuscarried out starting from the compound of formula (I) as defined above.

According to another aspect of the present invention, a subject-matterof the latter is a polysiloxane gel (IV) incorporatingpolyazamacrocycles and metal complexes of these nitrogenous ligands,which is capable of being obtained from the action of a metal salt onthe compound of formula (I) as defined above, resulting in the formationof an organometallic complex of said metal with said compound of formula(I), followed by the hydrolysis of said organometallic complex, and theprocess for the preparation of polysiloxane gel (IV) thus carried outstarting from the compound of formula (I) as defined above.

The metal involved in the composition of the polysiloxane gel (III) or(IV) is chosen in particular from U, Pu, Am, Eu, Ce, Cr, Gd, Mn, Fe, Co,Ni, Cu, Zn, Ag, Cd, Au, Hg or Pb.

A more particular subject-matter of the present invention is hybridmaterials (III₄) and (IV₁), corresponding respectively to the hybridcompounds (III) and (IV) in which the metal element is chosen fromcobalt or copper, and more particularly materials (III_(1a)) and(IV_(1a)) capable of being obtained from the compound of formula (Ia),(Ib) or (Ic).

In a final aspect of the present invention, a subject-matter of thelatter is the use of these metallated hybrid gels as defined above inseparating a predetermined gas from a mixture of gases, wherein saidmixture of gases is brought into contact with one of the metallatedhybrid gels (III) or (IV) as defined above under conditions which makepossible the absorption of said gas to be separated, followed by a phaseof desorption of said gas attached to said gel and by a phase ofrecovery of said desorbed gas. This use is preferably applied to theseparation of oxygen from the air, either for the purpose of producingpure oxygen or for the purpose of removing oxygen from the air.

The non-metallated gels (III′) can be employed in purifying liquidswhich absolutely have to be free from any metal cation, in particularthose used in the electronics industry, such as, for example, dilute orconcentrated hydrogen peroxide.

The non-metallated gels (III′) can also be employed in purifying gasesby adsorption of the undesirable gaseous impurities

The following examples illustrate the invention and in particular thetwo routes described above for the synthesis, according to a sol-gelprocess, of novel polysiloxanes incorporating polyazacycloalkanes andmetal complexes of these nitrogenous ligands.

As shown in these examples, the variety of the precursors used, theoptional addition of tetraalkoxysilane during the gelling stage and thevariations in the operating conditions make it possible to obtainmaterials with a variable composition and a variable texture, both interms of concentration of ligand or of complex in the solid and ofporosity and specific surface. Under strictly identical synthesisconditions, the solids obtained exhibit identical characteristics, thusshowing good reproducibility of the method.

The advantages of this method thus lie essentially in the possibility ofadjusting the characteristics of the material according to therequirements of materials engineering.

EXAMPLES

Various silica gels were synthesized by choosing1,4,8,11-tetraazacyclotetradecane (or cyclam) as organic ligand for thecoordination of the metal element. The various precursors were obtained,according to the following scheme, by reaction of the cyclam with fourequivalents of various silylated reactants of formula (C) to form thecorresponding compounds of formula (I). Several substituents terminatingin an —Si(OEt)₃ or —SiH₃ group were used: an aliphatic chain orsubstituents comprising an aromatic unit or an ester or amide functionalgroup.

The following compounds were thus prepared:

Compound 1

1,4,8,11-Tetrakis[3-(triethoxysilyl)propyl]-1,4,8,11-tetraazacyclotetradecane

2 g (0.01 mol) of cyclam and 12.41 g (0.09 mol) of K₂CO₃ in 100 ml ofCH₃CN (distilled over P₂O₅) are placed in a 200 ml Schlenk tube under anitrogen atmosphere. 13.27 g (0.04 mol) of (triethoxy)(3-iodo-propyl)silane are then added. The reaction mixture is brought toreflux for 12 h. After evaporating the solvent, the residue is taken upin 100 ml of pentane and filtered, and the precipitate is washed twicewith 30 ml of pentane. The filtrates are combined, the pentane isevaporated and compound 1 is obtained in the form of a slightly cloudyoil (9.85 g, 97%).

¹H NMR (200 MHz, CDCl₃) δ (ppm): 0.58 (m, 8H), 1.23 (t, 36H), 1.55 (m,12H), 2.39 (m, 8H), 2.51 (m, 8H), 2.54 (s, 8H), 3.83 (q, 24H). ¹³C NMR(50 MHz, CDCl₃) δ (ppm): 7.0, 17.3, 19.6, 21.9, 49.5, 50.4, 57.3, 57.9.²⁹Si NMR (40 MHz, CDCl₃) δ (ppm): −44.6. Elemental analysis forC₄₆H₁₀₄N₄O₁₂Si₄; Calculated: C. 54.33; H. 10.24; N. 5.51. Found: C.53.9; H. 9.93; N. 6.27.

Compound 2

1,4,8,11-Tetrakis[[4-(triethoxysilyl)phenyl]methyl]-1,4,8,11-tetraazacyclotetradecane

By carrying out the preparation in the same way as for compound 1, from1.5 g (0.0075 mol) of cyclam, 9.32 g (0.0675 mol) of K₂CO₃ and 11.4 g(0.03 mol) of (triethoxy) [4-(iodomethyl)phenyl]silane, a beige solid isobtained and, after recrystallization from 15 ml of ethanol, compound 2is obtained in the form of a white powder (6.5 g, 72%). M.p.=99.5-100.5°C. ¹H NMR (200 MHz, CDCl₃) δ (ppm): 1.29 (t, 36H), 1.77 (m, 4H), 2.54(t, 8H), 2.63 (s, 8H), 3.46 (s, 8H), 3.90 (q, 24H), 7.34 (d, 8H), 7.60(d, 8H). ¹³C NMR (50 MHz, CDCl₃) δ (ppm): 18.6, 24.4, 50.8, 51.9, 59.1,59.8, 128.8, 129.3, 135.0, 142.9. ²⁹Si NMR (40 MHz, CDCl₃) δ (ppm):−56.9. Elemental analysis for C₆₂H₁₀₄N₄O₁₂Si₄; Calculated: C. 61.58; H.8.61; N. 4.63; Found: C. 61.45; H. 8.81; N. 4.59.

Compound 3

Tetra[3-(triethoxysilyl)propyl]1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrapropanoate

0.5 g (0.0025 mol) of cyclam in 20 ml of ethanol are placed in a 100 mlSchlenk tube under a nitrogen atmosphere. 2.76 g (0.01 mol) of3-(triethoxysilyl)propyl acrylate are then added. The reaction mixtureis brought to reflux for 12 h. After evaporating the solvent, a cloudyoil is obtained, which oil is taken up in 10 ml of pentane and left for1 h at −20° C. The white precipitate formed is filtered, the filtrate isconcentrated and compound 3 is obtained in the form of a clear oil (2.36g, 72%).

¹H NMR (200 MHz, CDCl₃) δ (ppm): 0.51 (m, 8H), 1.24 (t, 36H), 1.44 (m,4H), 1.61 (m, 8H), 2.35 (t, 8H), 2.41 (t, 8H), 2.44 (s, 8H), 2.61 (t,8H), 3.69 (q, 24H), 3.90 (t, 8H). ¹³C NMR (50 MHz, CDCl₃) δ (ppm): 6.9,18.7, 22.6, 24.5, 32.9, 50.8, 51.1, 51.5, 58.7, 66.7, 173.1. ²⁹Si NMR(40 MHz, CDCl₃) δ (ppm): −45.6. Elemental analysis for C₅₈H₁₂₀N₄O₂OSi₄;Calculated: C. 53.37; H. 9.20; N. 4.29; Found: C. 53.17; H. 9.18; N.4.85.

By carrying out the preparation in the same way as hereinabove with2-(triethoxysilyl)ethyl acrylate,tetra[2-(triethoxysilyl]ethyl]1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrapropanoate(compound 8) is obtained.

Compound 4

1,4,8,11-Tetrakis(3-silylpropyl)-1,4,8,11-tetraazacyclotetradecane

7.47 g (0.00735 mol) of the compound obtained in Example 1 in 40 ml ofanhydrous ether are placed in a 150 ml Schlenk tube under a nitrogenatmosphere. A solution of 1.68 g (0.041 mol) of LiAlH₄ in 30 ml ofanhydrous ether is then added dropwise at 0° C. The reaction mixture isstirred for 24 h at room temperature and then excess LiAlH₄ is destroyedwith 5.5 ml of ethyl acetate at 0° C. After 30 min at room temperature,the solvents are evaporated. The residue is taken up in pentane, thesolid is filtered off and washed twice with pentane, and compound 4 isobtained in the form of an oil (2.83 g, 80%).

¹H NMR (200 MHz, CDCl₃) δ (ppm): 0.74 (m, 8H), 1.57 (m, 12H), 2.42 (t,8H), 2.52 (t, 8H), 2.55 (s, 8H), 3.53 (t, 12H). ¹³C NMR (50 MHz, CDCl₃)δ (ppm): 2.8, 21.9, 23.1, 49.5, 50.5, 56.9. ²⁹Si NMR (40 MHz, CDCl₃) δ(ppm): −58.7.

Compound 5

1,4,8,11-Tetrakis[(4-silylphenyl)methyl]-1,4,8,11-tetraazacyclotetradecane

3.75 g (0.0031 mol) of the compound obtained in Example 2 in 50 ml ofTHF are placed in a 200 ml Schlenk tube under a nitrogen atmosphere. Asolution of 0.70 g (0.018 mol) of LiAlH₄ in 20 ml of THF is then addeddropwise at 0° C. The reaction mixture is stirred for 1 h at 0° C. andthen for 12 h at room temperature. The excess LiAlH₄ is destroyed with 3ml of ethyl acetate. The reaction mixture is filtered through 20 g ofFlorisil® and the solvent is evaporated. The residue is taken up in 50ml of CH₂Cl₂ and filtered, and then the solvent is evaporated. 1.41 g ofcompound 5 are obtained in the form of a white powder (70%).

¹H NMR (200 MHz, CDCl₃) δ (ppm): 1.77 (m, 4H), 2.55 (t, 8H), 2.63 (s,8H), 3.45 (d, 8H), 4.23 (s, 12H), 7.32 (d, 8H), 7.51 (d, 8H). ¹³C NMR(50 MHz, CDCl₃) δ (ppm): 25.3, 51.0, 51.9, 59.8, 126.5, 129.1, 136.1,142.4. ²⁹Si NMR (40 MHz, CDCl₃) δ (ppm): −59.3. Elemental analysis forC₃₈H₅₆N₄Si₄; Calculated: C. 67.06; H. 8.24; N. 8.24; Found: C. 66.76; H.8.00; N. 8.06.

Compound 6

N₁,N₂,N₃,N₄-Tetrakis[3-(triethoxysilyl)propyl]-1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetamide

a) 38.2 ml (0.16 mol) of aminopropyltriethoxysilane and 23.6 ml (0.17mol) of triethylamine are dissolved in 70 ml of CH₂Cl₂ in a 150 mlSchlenk tube and then a spatula tip of 4-dimethylaminopyridine (DMAP) isadded. 26.95 g (0.17 mol) of bromoethanoyl chloride dissolved in 20 mlof CH₂Cl₂, are added dropwise at −30° C with stirring. The red viscoussolution obtained is stirred for 2 h at room temperature and then thesolvent is evaporated. The residue is taken up in 150 ml of ether; thesalts are filtered off and the solvent is evaporated. 48.84 g of a veryviscous brown product are obtained, which product, by distillation(127-132°/0.05 mm), results in 11.71 g (20%) of2-bromo-N-[3-(triethoxysilyl)propyl]acetamide [BrCH₂CONH(CH₂)₃Si(OEt)₃].

b) 0.5 g (0.0025 mol) of cyclam, 25 ml of acetonitrile and 3.1 g ofK₂CO₃ (0.0022 mol) are introduced into a 60 ml Schlenk tube. 3.76 g(0.011 mol) of the 2-bromo-N-[3-(triethoxysilyl)propyl]-acetamideprepared in stage a) are added dropwise with stirring. The reactionmixture is brought to reflux for 20 h. The solvent is subsequentlyevaporated. The residue is washed with 2×30 ml of warm pentane and isthen taken up in 70 ml of CH₂Cl₂. After filtrating and evaporatingCH₂Cl₂, 1.59 g (51%) of compound 6 are recovered in the form of a whitepowder.

¹H NMR (200 MHz, CDCl₃) δ (ppm): 0.64 (t, 8H), 1.23 (t, 36H), 1.63 (m,12H), 2.64 (m, 16H), 3.04 (s, 8H), 3.26 (m, 8H), 3.81 (q, 24H), 7.06 (m,4H). ¹³C NMR (50 MHz, CDCl₃) δ (ppm): 8.4, 18.7, 23.9, 24.9, 42.1, 51.4,52.6, 58.8, 59.1, 170.9. ²⁹Si NMR (40 MHz, CDCl₃) δ(ppm): −45.8.Elemental analysis for C₅₄H₁₁₆N₈O₁₆Si₄; Calculated: C. 52.09; H. 9.32;N. 9.00; Found: C. 49.55; H. 8.78; N. 9.34.

Compound 7

4,11-Bis[[4-(triethoxysilyl)phenyl]methyl]-1,4,8,11-tetraazacyclotetradecane-7,14-dione

2 g (0.0088 mol) of 7,14-dioxocyclam, 3.63 g (0.0026 mol) of K₂CO₃ and70 ml of anhydrous acetonitrile are introduced into a 200 ml Schlenktube. 6.7 g (0.018 mol) of (triethoxy)[(4-iodophenyl)methyl]silane areadded dropwise. The reaction mixture is brought to reflux for 12 h. Thesolvent is subsequently evaporated, the precipitate obtained is taken uptwice in 70 ml of CH₂Cl₂ and the solution is filtered. The solvent isevaporated and the solid is washed twice with 50 ml of pentane. 5.46 gof compound 7 are obtained in the form of a white powder whichrecrystallizes from a CH₂Cl₂/hexane (50/50) mixture. Yd 85%. M.p.163-164° C.

¹H NMR (200 MHz, CDCl₃) δ (ppm): 1.23 (t, 18H), 2.44 (m, 4H), 2.69 (m,8H), 3.44 (m, 4H), 3.71 (s, 4H), 390 (q, 12H), 7.28 (d, 4H), 7.68 (d,4H). ¹³C NMR (50 MHz, CDCl₃) δ (ppm): 18.6, 32.6, 36.2, 49.6, 52.5,57.8, 59.2, 129.5, 131.2, 135.4, 138.7, 172.5. ²⁹Si NMR (40 MHz, CDCl₃)δ (ppm): −57.9. Elemental analysis for C₃₆H₆₀N₄O₈Si₂; Calculated: C.59.01; H. 8.20; N. 7.65. Found: C. 58.91; H. 8.11; N. 7.73.

The hydrolysis of these compounds of formula (I) according to Route A orof the corresponding metal complexes (Route B) results in solids (III)and (IV) which exhibit different textures:

Cyclams carrying a single substituent with an —Si(OEt)₃ ending whichsubstituted or unsubstituted on the three remaining secondary aminefunctional groups have also been involved in a gelling process accordingto the following reaction:

In this case, the addition of tetraethoxysilane is necessary for thepolymerization of the precursor. A cogel is then obtained. Thiscogelling was also carried out in the other cases in order to study theinfluence of the addition of Si(OEt) ₄ in variable proportions on thetexture of the material obtained. The other gelling factors studied arethe nature of the solvent (MeOH, EtOH, THF, CH₂Cl₂, HCONH₂), theconcentration of the precursor (0.05 to 4 mol/dm³), the presence or theabsence of catalyst (NH₃ or tetraalkylammonium fluoride, such as TBAF)and the temperature (−20° C. to 150° C). The results are recorded in thefollowing Table 1; they show that, according to the gelling conditions,more or less condensed gels are obtained, this property being deducedfrom a ²⁹Si NMR study in the solid state; the degree of condensationincreases in the order T⁰<T¹<T²<T³ (Shea K. J., Loy D. A., Webster O.W.; Chem Mater., 1989, 1, 572-574). They also show, by BET analysis,that these more or less condensed gels exhibit different specificsurfaces and different porosities.

In the case of a precursor of formula (I) comprising several cyclicnitrogen atoms substituted by radical of general formula (B) as definedabove, cogels are also prepared by addition of tetraalkoxysilanes, suchas, for example, tetraethoxysilane.

Influence of the solvent (1M/TBAF/20° C.) (a) EtOH  17 min 370 m²/g T³ >T² (b) THF  27 min 343 m²/g (c) HCONH₂  30 min  2 m²/g (d) CH₂Cl₂  55min 454 m²/g Influence of the concentration (EtOH/TBAF/20° C.) (a) 1M 17 min 370 m²/g T³ > T² (e) 2M  10 min 470 m²/g T³ ˜ T² (f) 3M  7 min414 m²/g T³ > T² Influence of the catalyst (EtOH/1M/20° C.) (g) without 36 h  2 m²/g T⁰ > T¹ ˜ T² ˜ T³ (a) TBAF  17 min 370 m²/g T³ > T² (h)TBAF (sono)  15 min 410 m²/g T³ > T⁰ ˜ T¹ ˜ T² (i) NH₃ <24 h  0 m²/gInfluence of the temperature (EtOH/TBAF/1M) (a)  20° C.  17 min  370m²/g T³ > T² (j) 100° C. <30 min ˜800 m²/g Dilution with n Si(OEt)₄(EtOH/TBAF/1M/20° C.) (a) n = 0  17 min 370 m²/g T³ > T² (k) n = 1 <30min 386 m²/g (292^(a) + 95^(b)) T³ > T² Q³ = Q⁴ (l) n = 2 <30 min 428m²/g (290^(a) + 138^(b)) T³ < T² Q³ = Q⁴ (m) n = 5 <30 min 515 m²/g(299^(a) + 216^(b)) Si(OEt)₄ 3-4 h 470 m²/g (296^(a) + 174^(b))^(a)Microporous surface ^(b)External surface

TABLE 1 Factors influencing the texture of gels obtained by hydrolysis(6H₂O) of

Materials with different textures were obtained from the precursorcompounds (1) to (7). According to the experimental conditions (startingprecursor, temperature, solvent, catalyst), it was possible to obtainmaterials with predetermined specific surfaces ranging from 10 m²/g to800 m²/g, it being possible for the solids to be microporous, mesoporousor both simultaneously. The results are recorded in Table 2:

TABLE 2 Influence of the nature of the substituents on the texture ofthe material Precursor 100° C./ 100° C./ compound 20° C./EtOH 20° C./THF20° C./CH₂Cl₂ EtOH CH₂Cl₂ (1) 370 m²/g 350 m²/g 460 m²/g 800 m²/gmicropores micropores micropores mesopores gel (a) gel (^(b)) gel (d)gel (j) (2) <10 m²/g — 200 m²/g — 400 m²/g micropores gel (r₂) mesoporesgel (r₁) (3) <10 m²/g — — — — gel (s) (6) <10 m²/g — — — — gel (t) (4) —350 m²/g — — — micropores mesopores gel (u) (5) — <10 m²/g — — — gel (v)

Several metal salts were used for the metallation, before or aftergelling. They are Cu(OAc)₂, CuCl₂, Cu(BF₄)₂, Cu[B(C₆H₅)₄]₂, Cu[(PF₆)]₂,CuSiF₆, Co(OAc)₂, CoCl₂, Co(BF₄)₂, Co[B(C₆H₅)₄]₂, Co[PF₆]₂ and CoSiF₆.The amount of metal in the metallated gels was determined by X-rayfluorescence spectroscopy. The results are recorded in Tables 3 to 6.

TABLE 3 Metallation of the gels and cogels with CuCl₂ (Route A) Specificsurface before Specific surface metallation Ligand/metal aftermetallation [Cu⁺⁺] Gel (m²/g) stoichiometry (m²/g) (mmol/g) gel (j) 8001/2  80 1.33 (mesopores) gel (j) 800 1/1 250 0.83 gel (a) 370 1/2 <101.31 (micropores) gel (a) 370 1/1 <10 1.02 gel (g) <10 1/2 <10 1.33 gel(g) <10 1/1 <10 — gel (k) 390 1/2 <10 1.46 gel (l) 430 1/2 <10 1.25 gel(m) 510 1/2  15 0.74 gel (n) 690 1/2 550 0.59 gel (n) 690 1/1 625 — gel(o) 690 1/2 410 — gel (o) 690 1/1 550 — gel (p) 470 1/2 450 0 gel (r₂)400 1/1 <10 0.92 gel (r₁) 200 1/2 <10 1.59 gel (u) 350 1/2 100 1.78 gel(v) <10 1/2 <10 0.55

TABLE 4 Metallation of the gels with various Cu(II) salts (influence ofthe counterion) (Route A) Specific surface before Specific surfacemetallation after metallation [Cu⁺⁺] Gel (m²/g) Metal salt (m²/g)(mmol/g) gel (j) 800 CuCl₂ 250 0.83 (mesopores) gel (j) 800 CuSiF₆ <10 —(mesopores) gel (j) 800 Cu(OAc)₂.H₂O 280 0.85 (mesopores) gel (a) 370CuCl₂ <10 1.02 (micropores) gel (a) 370 CuSiF₆ <10 — (micropores) gel(a) 370 Cu(OAc)₂.H₂O <10 — (micropores) gel (a) 370 2Cu(OAc)₂.2H₂O <101.27 (micropores) gel (g) <10 CuCl₂ <10 — gel (g) <10 CuSiF₆ <10 — gel(g) <10 Cu(OAc)₂.H₂O <10 — gel (g) <10 2Cu(OAc)₂.2H₂O <10 1.44

TABLE 5 Metallation of the gels and cogels with CoCl₂ (Route A) Specificsurface before Specific surface metallation Ligand/metal aftermetallation [Co⁺⁺] Gel (m²/g) stoichiometry (m²/g) (mmol/g) gel (j) 8001/2 500 1.38 (mesopores) gel (j) 800 1/1 600 0.95 (mesopores) gel (a)370 1/2 <10 — (micropores) gel (a) 370 1/1 200 0.95 (micropores) gel (m)510 1/2 320 0.86 gel (r₁) 200 1/2 100 1.5  gel (r₁) 200 1/1 — 0.66 gel(u) 350 1/2 250 1.62 gel (v) <10 1/2 <10 1.56

TABLE 6 Gelling at 20° C. of complexed precursors (Route B) Metal of theprecursor Specific Precursor compound/metal surface [Metal] compoundcomplex (m²/g) (mmol/g) compound 1 Cu <10 0.95 compound 1 Co 10-20 0.90compound 2 Cu <10 0.97

The general experimental conditions are as follows:

Metallation of the Precursors)

The precursors are metallated with one or two equivalent(s) of metalsalt at reflux for 24 h. The solids obtained are washed with pentane andthen dried under vacuum.

Synthesis of the Gels

The precursor, the solvent, the necessary amount of water and thecatalyst are placed in that order in a pill machine. The gelling timet_(g) is measured from the moment when all the reactants have beenintroduced.

Three different treatments were subsequently applied to the gelsobtained:

a) aging for 5 days at room temperature, milling for 1 min, washing withethanol and with diethyl ether, and then drying at 120° C./3-20 mmHg for12 h

b) aging for 2 days at room temperature and then the same treatment asa)

c) aging for 5 days at 100° C. (gellings in sealed tubes) and then thesame treatment as a)

Metallation of the Gels

The metallations are carried out according to two methodologies:

a) Cu(II) complexes

The material and the copper salt (1 or 2 eq.) are placed in 20 ml ofabsolute ethanol in a 100 ml round-bottomed flask. The reaction mixtureis brought to reflux for 12 h and the metallated material is filteredoff, washed with ethanol and diethyl ether and, finally, dried at 120°C./3-20 mmHg for 12 h.

b) Co(II) complexes

The material and the cobalt salt (1 or 2 eq.) are placed in 20 ml ofdistilled ethanol in a 100 ml Schlenk tube under a nitrogen atmosphere.The reaction mixture is brought to reflux for 12 h and the metallatedmaterial is filtered off and washed with ethanol.

Gelling of the Metallated Precursors

The metallated precursors are gelled according to a procedure identicalto the gelling of the non-metallated precursors.

During the gelling stages described hereinabove, use is generally madeof the following solvents:

dimethylformamide (DMF), ethanol, methanol, tetrahydrofuran (THF),acetonitrile, dioxane or acetic acid;

the catalyst is generally chosen from acidic catalysts (H⁺), basiccatalysts (OH⁻) or nucleophilic catalysts, such as F⁻ in the form ofammonium fluoride or of tetrabutylammonium fluoride,N,N-dimethyl-aminopyridine (DMAP), N-methylimidazole orhexamethylphosphoramide (HMPA).

Several oxygenation tests on metallated gels were carried out using anautomatic adsorption bench tester based on the volumetric principle. Theresults are recorded in Table 7.

TABLE 7 Metal salt Specific Volume O₂ Ligand/metal surface [Co⁺⁺]adsorbed Gel stoichiometry (m²/g) (mmol/g) (Scc/g) gel (o) CoCl₂ 1/1 6900.19 1.23 gel (a) CoCl₂ 1/1 600 0.95 1.70 gel (j) CoCl₂ 1/1 200 0.952.30

A novel series of gels and/or cogels was prepared and the reactivity ofthese materials with respect to dioxygen and dinitrogen was studied bymeasuring the adsorption at 294K of said gases, by the decrease in thepressure at constant volume, using a Micromeritics adsorption benchtester.

The results are recorded in the following table:

TABLE 8 Gel (BET Degassing N₂ O₂ [M²⁺] O₂/N₂ Precursor in m² · g⁻¹)Metal Counterion 10⁶ torr Scc/g Scc/g mmol/g Selectivity Compound (1)(1a) Cu²⁺ 2 Cl⁻ 1st cycle: 0.40 6.19 0.86 15.5 (480, 20° C., 24 h(meso)) 2nd cycle: 1.57 3.9 20° C., 3 h Compound (1) (1b) Cu²⁺ 2 Cl⁻ 1stcycle: 0.18 4.61 1.00 25.6 (75, 20° C., 24 h (meso)) 2nd cycle: 2.5013.8 20° C., 18 h Compound (1) (1c) Cu²⁺ 2 Cl⁻ 1st cycle: 0.40 7.01 1.1217.5 20° C., 24 h 2nd cycle: nd 11.07 27.6 120° C., 24 h 3rd cycle: 0.357.20 20.6 120° C., 24 h Compound (1) + (1d) ½Cu²⁺ Cl⁻ 1st cycle: 0.450.47 0.21 1 10 20° C., 24 h Si(OEt)₄ 2nd cycle: 0.54 0.75 1.38 120° C.,24 h Compound (1) (1e) Co²⁺ 2 Cl⁻ 1st cycle: 0.51 0.51 1.49 1 20° C., 24h 2nd cycle: 0.41 0.43 1 120° C., 24 h Compound (1) (1f) ½ Co²⁺ Cl⁻ 20°C., 24 h 0.61 0.66 1.05 1.08 (417, (meso)) Compound (8) + (8a) ½ Co²⁺Cl⁻ 1st cycle: nd 1.54 0.35 nd 10 (cogel) 120° C., 24 h Si(OEt)₄ (250,2nd cycle: nd 1.49 nd (meso)) 100° C., 2 h Compound (2) (2a) Co²⁺ 2 Cl⁻20° C., 24 h nd 0.66 1.64 nd Compound (9) (9a) Co²⁺ 2 Cl⁻ 1st cycle: 1.01.46 1.57 14.6 20° C., 24 h 2nd cycle: 1.0 0.88 8.8 120° C., 3 h 3rdcycle: 1.0 3.71 37 120° C., 7 h 4th cycle: nd 2.40 nd 120° C., 7 hCompound 9 is1-[3-(triethoxysilyl)propyl]-1,4,8,11-tetraazacyclotetradecane.

What is claimed is:
 1. A compound of formula (I):

in which: W₁, W₂ and W₃, which are identical or different, eachrepresent, independently of one another, a divalent radical chosen fromthose represented by the general formula (A):—[(CT₁T₂)_(n)—N[(R₄)]_(p)—(CT₃T₄)_(m)]_(l)—  (A)  in which: p representsan integer equal to 0 or to 1, l represents an integer equal to 1 or to2, n and m, which are identical or different, each represent,independently of one another, an integer less than or equal to 3 andgreater than or equal to 1, T₁, T₂, T₃ and T₄, which are identical ordifferent, either each represent, independently of one another, ahydrogen atom, a linear or branched alkyl radical comprising from 1 to15 carbon atoms or benzyl, [2-pyridyl)methyl], [3-pyridyl)methyl] orphenethyl or else CT₁T₂ and/or CT₃T₄ represent a divalent group —(C═O)—,R₁, R₂, R₃ and R₄ represent radical represented by the general formula(B): R₅—Si(X₁)(X₂)(X₃)  (B)  in which: X₁, X₂ and X₃, which areidentical or different, each represent, independently of one another, ahydrogen atom, a halogen atom or an OR₆ radical, in which R₆ representsa hydrogen atom or an alkyl radical comprising from 1 to 4 carbon atoms,R₅ represents a divalent radical derived from a saturated or unsaturatedaliphatic hydrocarbon chain comprising from 1 to 10 carbon atoms, inwhich chain are optionally inserted one or more structural links chosenfrom the arylene group or the —O—, —S—, —O—C(═O)—, —N(R₇)—C(═O)— or—N(R₇)— fragments, in which fragments R₇ represents a hydrogen atom, analiphatic hydrocarbon radical comprising from 1 to 6 carbon atoms, abenzyl radical or a phenethyl radical, said chain being unsubstituted orsubstituted by one or more radicals chosen from halogen atoms, thehydroxyl group, alkyl radicals comprising from 1 to 4 carbon atoms orbenzyl or phenethyl radicals.
 2. A compound of formula (Ic),corresponding to the formula (I) as defined in claim 1 in which W₁ andW₂, which are identical or different, represent a divalent radical offormula (A₂), corresponding to the formula (A) in which p is equal to 1and the sum n+m is equal to 2 or to 3, and W₃ represents a radical offormula (A₁), corresponding to the formula (A) in which p is equal to 0and the sum n+m is equal to 2 or to
 3. 3. The compound of formula (I) asdefined in claim 1, in which the radical of formula (B) is selected fromthe group consisting of 3-silylpropyl, (4-silylphenyl)methyl,3-(triethoxysilyl)propyl,3-[[3-(triethoxysilyl)propyl]oxy]-2-hydroxypropyl,[4-[[[3-(triethoxysilyl)propyl]amino]methyl]phenyl]methyl,[4-(triethoxysilyl)phenyl]propyl,3-oxo-3-[[3-(triethoxysilyl)propyl]oxy]propyl and2-oxo-2-[[3-(triethoxysilyl)propyl]amino]ethyl radicals.
 4. Thecompounds of formula (I) as defined in claim 1 with the following names:1,4,8,11-tetrakis[3-(triethoxysilyl)propyl]-1,4,8,11-tetraazacyclotetradecane,1,4,8,11-tetrakis[[4-(triethoxysilyl)phenyl]methyl]-1,4,8,11-tetraazacyclotetradecane,tetra[3-(triethoxysilyl)propyl]1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrapropanoate,1,4,8,11-tetrakis(3-silylpropyl)-1,4,8,11-tetraazacyclotetradecane,1,4,8,11-tetrakis[(4-silylphenyl)methyl]-1,4,8,11-tetraazacyclotetradecane,N₁,N₂,N₃,N₄-tetrakis[3-(triethoxysilyl)propyl]-1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetamide,or4,11-bis[[4-(triethoxysilyl)phenyl]methyl]-1,4,8,11-tetraazacyclotetradecane-7,14-dione.5. A polysiloxane gel (IV) incorporating polyazamacrocycles and metalcomplexes of these nitrogenous ligands, which is capable of beingobtained from the action of a metal salt on the compound of formula (I)as defined in claim 1, resulting in the formation of an organometalliccomplex of said metal with said compound of formula (I), followed by thehydrolysis of said organometallic complex.
 6. A compound of formula(Ia), corresponding to the formula (I) as defined in claim 1 in whichW₁, W₂ and W₃, which are identical or different, represent a radical offormula (A₁), corresponding to the formula (A) in which p is equal to 0and the sum n+m is equal to 2 or to
 3. 7. A compound of formula (Ia₁),corresponding to the formula (Ia) as defined in claim 2, in which l isequal to 1 and either W₁, W₂ and W₃ each represent the divalent radical—CH₂—CH₂—CH₂— or else any one of the three groups W₁, W₂ or W₃represents the divalent radical —CH₂—CH₂—CH₂— and each of the other twogroups represents the divalent radical —CH₂—CH₂—.
 8. A compound offormula (Ib), corresponding to the formula (I) as defined in claim 1 inwhich W₁ represents a divalent radical of formula (A₂), corresponding tothe formula (A) in which p is equal to 1 and the sum n+m is equal to 2or to 3, and W₂ and W₃, which are identical or different, represent aradical of formula (A₁), corresponding to the formula (A) in which p isequal to 0 and the sum n+m is equal to 2 or to
 3. 9. A compound offormula (Ib₁), corresponding to the formula of (Ib) in claim 3, in whichl is equal to 1 and either any one of the three groups W₁, W₂, or W₃represents the radical —CH₂—CH₂—CH₂—N(R₄)—CH₂—CH₂—, either one of thetwo remaining groups represents the radical —CH₂—CH₂— and the finalgroup represents the racial —CH₂—CH₂—CH₂— or else any one of the threegroups W₁, W₂ or W₃ represents the radical—CH₂—CH₂—CH₂—N(R₄)—CH₂—CH₂—CH₂— and the other two remaining groups eachrepresent the radical —CH₂—CH₂—CH₂—.
 10. A polysiloxane gel (III)incorporating polyazamacrocycles and metal complexes of thesenitrogenous ligands, which is capable of being obtained from thehydrolysis of the compound of formula (I) as defined in claim 1,resulting in the formation of a polysiloxane gel incorporatingnon-metallated polyazamacrocycle units (III′), followed by the action ofa metal salt on said gel (III′).
 11. A method of purifying a liquid fromcationic impurities, wherein said liquid is brought in contact with apolysiloxane gel incorporating non-metallated polyazamacrocycle units(III′) as defined in claim
 10. 12. A process for the preparation of thepolysiloxane gel (III), wherein the compound of formula (I) as definedin claim 1 is subjected to hydrolysis, resulting in the formation of apolysiloxane gel incorporating non-metallated polyazamacrocycle units(III′), and then wherein said gel (III′) is reacted with a metal salt.13. A process for the preparation of the polysiloxane gel (IV), whereinthe compound of formula (I) as defined in claim 1 is reacted with ametal salt, resulting in the formation of an organometallic complex ofsaid metal with said compound of formula (I), and then wherein saidorganometallic complex is subjected to hydrolysis.
 14. An alternativeform of the process as defined in claim 12 or 13, in which the metalcation involved in the composition of the polysiloxane gel (III) or (IV)is selected from the cations consisting of Cu²⁺ and Co²⁺.
 15. A methodof separation of a predetermined gas from a mixture of gases whereinsaid mixture of gases is brought into contact with one of the metallatedhybrid gels (III) as defined in claim 12, under conditions which makepossible the absorption of said gas to be separated, followed by a phaseof desorption of said gas attached to said gel and by a phase ofrecovery of said desorbed gas.
 16. A method as defined in claim 15,wherein the mixture of gases is air and the gas to be separated isoxygen.
 17. A method of separation of a predetermined gas from a mixtureof gases wherein said mixture of gases is brought into contact with oneof the metallated hybrid gels (IV) as defined in claim 13, underconditions which make possible the absorption of said gas to beseparated, followed by a phase of desorption of said gas attached tosaid gel and by a phase of recovery of said desorbed gas.
 18. A methodas defined in claim 17, wherein the mixture of gases is air and the gasto be separated is oxygen.